[R] 3dscatterplot -different colors for different factors of the same variable

[Dieter Menne]

Moreno Ignazio Coco <M.I.Coco <at> sms.ed.ac.uk> writes:

> I was trying to do a 3d scatterplot for the following set of datas:
> 
>          "obj"  "time" "X" "Y"
> "1"  "yellow"  "333" "388.7" "492.3"
> "2"  "yellow"  "567" "388.7" "492.3"
> "3"  "green"   "621" "135.5" "371.7"
> "4"  "green"   "1039" "135.5" "371.7"
> "5"  "red"     "1373" "744.1" "205.0"
> "6"  "red"     "1763" "744.1" "205.0"
> 
> The points should be drew in the plot taking information of "time",  
> "X" and "Y". The colors of these points should be assigned according  
> to the information contained in variable "obj".
> What I did but it didn't work out is:
> 
> 1) Plotting only one set of points (the green one)
> 
> s3d<-scatterplot3d(greenpts[,3],greenpts[,2],greenpts[,4],type="p",scale.y=4,  
> angle=10, color="green")

This does not plot the "green" points (you did not tell us how to get the data,
please show the way you read these in). With a bit of guessing, I assume that
you plotted all 6 points in green.
 
> and try to overlay the others (as you normally would do with "plot"):
> s3d$points3d(redpts[,3],redpts[,2],redpts[,4],col="red",type="o")

I don't understand this one. Try the following

#  See also http://finzi.psych.upenn.edu/R/Rhelp02a/archive/62479.html
library(scatterplot3d)
pts = read.table("d3data.txt")
pts
# gives for me:
#     obj time     X     Y
#1 yellow  333 388.7 492.3
#2 yellow  567 388.7 492.3
#3  green  621 135.5 371.7
#4  green 1039 135.5 371.7
#5    red 1373 744.1 205.0
#6    red 1763 744.1 205.0

# must use larger points and pch=16 here, otherwise yellow is almost invisible
scatterplot3d(pts$X,pts$time,pts$Y,type="p",scale.y=4,  
angle=10, color=pts$obj,pch=16)

# Here come the two rgl-base alternatives. Note that rgls for historical reasons
has two interfaces which you should not mix; only use one of the two methods.
You can rotate the rgl plot with the mouse, and also add axis. 

rgl is an amazing package; thanks, Duncan. 

Dieter

library(rgl)
# 3d interface
open3d()
points3d(x=pts$X,y=pts$time,z=pts$Y,pch=16,color=pts$obj,size=5)

# rgl.* interface
rgl.open()
rgl.points(x=pts$X,y=pts$time,z=pts$Y,pch=16,color=pts$obj,size=5)